The present invention relates to media for reception of liquid such as absorption, retention, and transfer components of personal care products like disposable diapers, training pants, swimwear, incontinent protective devices and feminine care sanitary napkins and the like. While many improvements have been made to liquid reception media for these and other uses, some products still tend to be bulky and, in use, cause the wearer to be self conscious. Moreover, packaging, shipping and storage of such bulky products represent significant costs. Finally, disposal of used product has been indicated by some to represent an opportunity for environmental improvement. It has been long recognized that a more efficient medium for receiving, transfer and/or absorption would permit significant reduction in the amount of absorbent material needed and favorably impact each of the above issues. The present invention is directed to such a liquid reception medium.
One measure of the efficiency of a liquid absorbent medium is its ability to move the liquid being absorbed within the medium from the point of delivery to areas throughout the entire absorbent medium so that the total available capacity of the medium to absorb is utilized. Much research effort has been expended developing ways to accomplish this movement of liquid. For example, special fiber shapes and spacing have been used to create and enhance the capillary forces which cause fluids to move in an absorbing medium, and treatments have been developed that act on liquids being absorbed and the absorbing medium itself. In addition, the configuration of the medium has been modified such as by creating embossed channels or folds intended to direct liquid movement. While these efforts have had a measured degree of success, there remains a need for even better measures to quickly move relatively large liquid volumes (insults) from a delivery or target zone to a peripheral area either within the liquid receiving component or in another absorbent component. The result will reduce leakage and/or allow reduced amounts of absorbent material to be used to make more conforming products and provide environmental benefits.
Capillary movement of liquids either using the capillary structure between fibers or pore structures within foams, for example, is relatively slow. Movement of mass quantities of liquid resulting from gush or surge insults can, of course, be accomplished by collecting the liquid and displacing it by physical means to another area of the absorbent product. Practical means for accomplishing this displacement, however, are not well defined or developed to date. One effort described in U.S. Pat. No. 5,769,834 to Reiter et al., relies on an apertured tube and pumping action from decompression and compression by bodily movements of a wearer of a diaper, as an example. The liquid movement is thus dependent on the movement of the wearer. U.S. Pat. No. 5,902,297 to Sauer is directed to an absorbent article with conduit means for collecting and transporting fecal matter. The present invention relates to different mechanical structures of absorbent product components to accomplish the desired result in a reliable and effective manner.
The present invention provides a liquid reception device having one or more component layers and that includes a layer having a target zone and that includes in the device a peripheral absorption zone either within or outside the layer having a target zone. A liquid transport means is included within the target zone and extends to the peripheral zone. Upon liquid contact the liquid transport means is activated to move a mass amount of liquid from the target zone to a peripheral zone. The liquid transport means can be, for example, a tube which is connected to a suction device and is sealed by a liquid dissolvable seal. When contacted by liquid, the seal is dissolved and the end of the tube or other previously sealed part opened to draw liquid by means of the suction device. Another means can be a collapsed sealed tube containing a liquid expandable material such as a superabsorbent or collapsed foam. When the seal is dissolved, the collapsed tube is forced to expand. The expansion creates a void volume and thus a vacuum. The liquid is pulled into the tube by the vacuum. As the liquid contacts the superabsorbent, the superabsorbent swells, causing the tube to further expand. Ideally, the tube will readily expand to a larger dimension that its original, pre-compressed dimension so the absorption/expansion/vacuum generation cycle will continue. Another transport means includes a collection device attached by a dissolvable adhesive in the target zone and also by elastic means to an area in the peripheral zone. Liquid contact causes the collection means to be released from the target zone and displaced to the peripheral zone. The collection device could be a stretched superabsorbent fiber which is permanently attached in the periphery of the product and attached in the target area by a slowly dissolving water soluble adhesive. The filament would absorb liquid, the adhesive dissolve, and be pulled up into the periphery of the product. In all cases the structure requires only liquid contact to activate the mechanical liquid transport means.